I've used P Clips in the past.Just an FYI: I searched and browsed through the articles and forums here on BYC, but could not find one description of how a solid back was attached to the cattle panel hoop. I did see one photo where it looked as if they'd used plumber's strap, but my siding is only 1/3" thick, so screws wouldn't work very well.
https://nyfast.com/home/10290-p-clips-stainless-steel
Stronger than zip ties and plastci clips. A nut and bolt through the plywood makes a very strong join.